What does 5w40 mean for engine oil?
2 Answers
Engine oil labeled as 5w40 means the vehicle can use this type of oil in environments ranging from -35°C to 40°C. Below is more information about engine oil: 1. Composition: Engine oil consists of base oil and additives. The base oil is the main component of lubricating oil, determining its fundamental properties, while additives compensate for and improve any deficiencies in the base oil's performance, providing new characteristics and being an essential part of the lubricating oil. 2. Function: Reduces wear and extends the engine's service life. 3. Performance: Lubricity; low-temperature operability; viscosity-temperature characteristics; oxidation resistance; foam resistance. 4. Checking the shelf life: The simplest way to check the shelf life of engine oil is to observe whether the oil's viscosity has changed, determine if the oil's smell has faded, and observe if the oil's color has changed. When observing changes in the oil's color, pay attention to changes in the additives within the oil.
The oil grade 5W40 is actually a viscosity indicator, and I really enjoy studying these automotive details. The 5W in 5W40 indicates its fluidity at low temperatures, with the number 5 showing that it flows easily even in sub-zero winter conditions, allowing for quicker and smoother engine starts. The 40 represents the oil film thickness at high temperatures, where a higher number means better protection against engine wear. This entire grading system is based on the SAE international standard, essentially measuring how the oil performs under different temperatures. Why is it important? Because choosing the right oil protects your engine, especially by reducing dry friction damage during cold starts in winter, thereby extending engine life. For instance, in northern winters like mine, 5W30 or 5W40 is commonly used to ensure the car runs smoothly. Additionally, when changing oil, always refer to the car manual to match the appropriate viscosity for optimal performance. I recommend regularly checking the oil condition and changing it promptly if it appears cloudy.
